Programme of research into the management and storage of radioactive waste. Backfilling and sealing

This report concerns the release of radionuclides from radioactive waste disposed of in deep stable geological formations by transport in the ground water. The programme attempts to reproduce, in the laboratory on a reduced scale, the near field of a repository, i.e. the region comprising waste, canister, back-fill, and adjacent geological formation. Results are presented for the leaching of simulated vitrified high level waste by Cornish granite groundwater. The simulated waste was doped with Tc-99, Cs-137, Np-237, Am-241, and a mixture of Pu isotopes. The leachate is then passed through a packed bed of iron oxides (representing the corroded canister), powdered concrete (the back-fill) and granite particles. Results are given and discussed. (U.K.)